There is disclosed a discharge system which performs the discharge of a secondary battery to diagnose the life span of the secondary battery (see, e.g., Japanese Patent Application Publication No. 2005-43059). In such a discharge system, there are cases where a temperature of the secondary battery rises when the secondary battery is discharged, or where an over-discharge occurs in one of cells if there is a voltage difference between the cells in the secondary battery including two or more cells connected in series. This requests a measure in the aspect of safety and life span of the secondary battery.
Further, the conventional discharge system can be applied only to existing secondary batteries. Therefore, even if a secondary battery with, e.g., a different total battery voltage is newly provided, the conventional discharge system cannot be applied to the new secondary battery.